Zebra Danio Swimming Sideways

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Aquarium Advice Newbie
Jul 19, 2022
5 and 1/2 year old female zebra danio. Lives with one other zebra danio (male) in a 10g tank. Water changes every two weeks since such a low bioload. Ammonia 0, Nitrite 0, Nitrates stay under 20. Fully cycled tank, they have been in this tank for over a year. I feed Tetra Color Tropical Flakes, they struggle to eat pellets. Occasionally frozen emerald entree or peas. Been doing biweekly water changes since I’ve noticed she was swimming a bit odd. She’s lopsided. She swims almost on her side. She is also clamping some of her fins on the side of the body she is leaning towards. They don’t appear torn. I don’t notice any visible injuries or other symptoms. Her scales are not raised; I don’t suspect dropsy. I haven’t introduced anything new to tank including plants. I fed emerald entree, fasted for a day, then fed a pea. This has been going on about 5 days and at first she would hang around top of tank but for 2 days she’s been hiding at the bottom and very lethargic. I can tell that she might pass. I want to try and save her while also not stressing her out. She is old. I use Seachem Prime for water changes. Clearly something might be up with her swim bladder. I know she’s old but she’s been in good health. I’ve been adding Seachem Stress Guard daily to cover some bases. The male tank mate has not showed any symptoms. She ate some flaked food today. How can I tell if swim bladder disease is caused by a bacterial infection? Any advice on how to keep her comfortable or to help her?


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Over 5 years is very old for a zebra danio. In the wild they don't often make it much past 1 year. As with people, as they get older they get sick easier and are less likely to recover. If its a swim bladder problem rather than just bloating or constipation then thats not treatable.

You could try not feeding for a few days, and then try feeding a pealed boiled pea see if that sorts things out, but i dont see it helping a fish that is well past its expected lifespan.

You will have to make a decision on whether your fish is suffering. If its able to swim and eat then just leave it be. If not then consider euthanising the fish. Trying to treat something that simply isnt treatable isnt going to help.
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